import matplotlib.pyplot as plt

weight = [50, 60, 30, 70, 90, 100, 48]
power = [90, 27, 37, 86, 46, 88, 100]

# 自定义坐标系起始，否则默认自适应
plt.axis([0,120,0,150])

plt.scatter(weight, power)
# 保存为图片
plt.savefig('scatter04.jpg')